Explanation: Lead-acid cells should be kept warm at low temperatures for two main reasons. First, (A) to prevent freezing: the electrolyte in a lead-acid battery is a mixture of sulfuric acid and water. As the battery discharges, the sulfuric acid is consumed, and the concentration of water increases. Water has a higher freezing point than sulfuric acid, so a discharged battery is much more susceptible to freezing, which can permanently damage the plates and casing. Second, (B) to provide the maximum capacity: low temperatures drastically reduce the chemical reaction rate within the battery. This slowdown means the battery cannot deliver its full rated capacity or supply as much current as it could at warmer temperatures. Keeping the battery warm ensures the chemical reactions occur efficiently, allowing the battery to deliver its maximum design capacity and power. Therefore, both reasons are critical for battery longevity and performance.